This invention relates generally to computed tomographic (CT) imaging, and more particularly to methods and apparatus for operating a CT radiation source.
At least one known CT imaging system uses a fan-beam based helical algorithm to generate images that may include a significant noise in-homogeneity and an increased noise level. The noise in-homogeneity is mainly caused by an interaction between the helical weighting and a weighting factor in a fan beam backprojection. The noise variation within the scan field of view can vary more than a factor of two, even for a homogeneous scanned object. The noise in-homogeneity can increase away from an iso-center and may also generate image artifacts, such as Venetian blinds or zebra, in the three-dimensional reformatted images.
In one aspect, a method for reconstructing an image of an object is provided. The method includes generating a plurality of projection data, helically interpolating the projection data, rebinning the helically interpolated projection data from a fan-beam format to a parallel-beam format, and reconstructing an image of the object using the parallel-beam format projection data.
In another aspect, a method for reconstructing an image of an object is provided. The method includes generating a plurality of projection data, helically interpolating the projection data, rebinning a first set of original measured projections wherein an angular increment between at least two views is uniform, rebinning a first set of interpolated projections wherein the angular increment between at least two views is uniform, and combining the first set of original measured projections and the first set of interpolated projections to reconstruct an image of an object.
In still another aspect, a method for reconstructing an image of an object is provided. The method includes rebinning a first set of original measured projections wherein an angular increment between at least two views is uniform, rebinning a first set of interpolated projections wherein the angular increment between at least two views is uniform, and combining the first set of original measured projections and the first set of interpolated projections to reconstruct an image of an object.
In yet another aspect, a computed tomographic (CT) imaging system for reconstructing an image of an object is provided. The CT system includes a radiation source, a detector array, and a computer coupled to the detector array and the radiation source. The computer is configured to generate a plurality of projection data, helically interpolate the projection data, rebin the helically interpolated projection data from a fan-beam format to a parallel-beam format, and reconstruct an image of the object using the parallel-beam format projection data.
In yet still another aspect, a computed tomographic (CT) imaging system for reconstructing an image of an object is provided. The CT system includes a radiation source, a detector array, and a computer coupled to the detector array and the radiation source. The computer is configured to generate a plurality of projection data, helically interpolate the projection data, rebin a first set of original measured projections wherein an angular increment between at least two views is uniform, rebin a first set of interpolated projections wherein the angular increment between at least two views is uniform, and combine the first set of original measured projections and the first set of interpolated projections to reconstruct an image of an object.
In still yet another aspect, a computer readable medium encoded with a program executable by a computer for reconstructing an image of an object is provided. The program is configured to instruct the computer to generate a plurality of projection data, helically interpolate the projection data, rebin the helically interpolated projection data from a fan-beam format to a parallel-beam format, and reconstruct an image of the object using the parallel-beam format projection data.
In still yet another aspect, a computer readable medium encoded with a program executable by a computer for reconstructing an image of an object is provided. The program is configured to instruct the computer to generate a plurality of projection data, helically interpolate the projection data, rebin a first set of original measured projections wherein an angular increment between at least two views is uniform, rebin a first set of interpolated projections wherein the angular increment between at least two views is uniform, and combine the first set of original measured projections and the first set of interpolated projections to reconstruct an image of an object.